Conventionally, there is known a key switch device having a gear link structure in which a pair of link members is assembled to be interlocked by meshing their ends with each other (for example, see Japanese Patent Laid-Open No. 2009-76321).
A key switch device includes a key top, the pair of the link members interlocked with each other to move the key top vertically upward and downward, a support plate, and a frame member for attaching one ends of the link members to the support plate. The frame member is formed with bearing portions into which pivot shaft portions provided in the pair of the link members are fitted respectively. Also, the frame member has leg portions extending vertically downward. The support plate has circular-shaped through holes through which the leg portions of the frame member respectively penetrate.
The bearing portions of the frame member respectively receive the pivot shaft portions of the link members, and the leg portions of the frame member respectively penetrate through the through holes of the support plate, whereby the pair of the link members is pivotally attached on the support plate. Ends of the leg portions of the frame member respectively penetrating through the through holes of the support plate are deformed by thermal caulking, which fixes the frame member on the support plate.